HTR2A and Parkinson disease: Pimavanserin’s discovery and launch as the first evidence-based FDA-approved pharmacotherapy for PDP, circumvents all those complications from off-label therapies and has a placebo-like effect on the motor symptoms of PD because it is a potent, highly selective 5-hydroxytryptamine (serotonin) 2A receptor (5-HT2A) inverse agonist with no appreciable affinity to dopamine D2 receptors.